leejp,

I just finished replumbing my system and will pass on the lessons learned:

1) If you have some parts that you know the exact dimensions and geometry of the setup, you can do that in your workshop. I did that with a couple of diverter valves, a check valve and associated elbows. Otherwise, as Matt4x4 advises, do the rest on site.

2) Make sure your pump and filter are level with each other and the ground. This ensures you piping will square up without putting any stain on the pump and filter fittings. I had to shim up a filter that was nearly 10 degrees out of level.

3) Technically, 1.5 - 2.0" PVC requires 30 minutes after gluing before movement, but practically you can proceed after 1-2 minutes if you handle the joints gently. Be SURE to HOLD the joints together for 30 seconds after insertion as they will tend to back out. This can take quite a bit of force on 2" fittings, so be sure you are in a good potion to exert the required force. Here are some good links on gluing techniques:
http://www.ppfahome.org/faq-cement.html
http://www.aquaticeco.com/index.cfm/...Detail/ttid/15
http://www.elchem.com/making_solvent_cem_joints.htm

4) If you have any long runs with heavy components (valves, unions, SWCG's) be sure to provide some support along the way.

5) For alignment I used a framing square, plumb bob, tape measure and sharpie to map out, mark and check the route during assembly.

6) Use unions wherever you will need to remove something for maintenance or replacement. They are cheap at Lowe's and worth every penny.

7) Lastly, measure and remeasure before cutting, including accurate measures of the insertion depths of the pipe/fittings.